A backup operation is apt to be complicated, but if there is a mechanism whereby data written on a first storage device, such as a hard disk drive (HDD), can be easily and conveniently duplicated in another file system, it is possible to prevent data loss due to failure of the first storage device.
In some backup approaches RAID1 (mirroring) technology is used, which duplexes the data written to a HDD. RAID1 writes identical data onto plural disks by random block access based on a block by block basis, and is generally limited to use of HDDs, due to the use of random access capability.
File systems, such as LTFS (linear tape file system) enable sequential access of data on a tape drive (TD) as a file in a file system. By using a file system such as LTFS, the use and versatility of tape storage is enhanced.
On the tape drive, a read/write command does not specify a block number which differs from a read/write command of a block device, such as an HDD. The read/write command of the tape drive specifies that a read/write be carried out at the current tape position, and when the command is successful, the current position is updated. The current position can be acquired using a “read position” command, and the current position may be set at any location using a locate/space command.